useful service life

基本解释

This nm-class hydrophilic aluminum foil heat exchanger can prolong its useful service life for 5-10 years, although it costs 3 times more than the conventional aluminum foil heat exchanger.
雖然納米親水鋁箔換熱器的制作成本高於一般用鋁箔換熱器，但它卻能使換熱器的使用壽命延長5-10年。
Living examples in repair of air hammer parts by manual bead welding of electrical are have been introduced, which are useful for lengthening service life of air hammer parts and saving cost.
介紹了用手工電弧堆銲的方法將一些空氣鎚零件脩複的實例，對延長空氣鎚零件的使用壽命、約生産成本有一定的蓡考價值。
Living examples in repair of air hammer parts by manual bead welding of electrical are have been introduced, which are useful for lengthening service life of air hammer parts and saving cost.
介紹了用手工電弧堆銲的方法將一些空氣鎚零件脩複的實例，對延空氣鎚零件的使用壽命、節約生産成本有一定的考價值。

In practice, however, it is a formula for condemning America's armed forces to operating obsolete equipment long after its useful service life is ended -- and inviting others to perceive and perhaps to act upon exploitable weaknesses on the part of the United States.
CENTERFORSECURITYPOLICY: Center For Security Policy
Anyone who has taken a life-saving medication or paid for a useful service, for example, has left behind a profit for the provider and is thankful for the benefits received.
FORBES: Success and Social Value